Does ChatGPT read JavaScript on my website?

No. They read the HTML your server returns, and stop there.

The short answer is no, and it matters more than it sounds. If your site is built with a framework that renders in the browser, the HTML arriving at an AI crawler may contain your navigation, your fonts and an empty <div> where the content goes.

What the crawler actually receives

One request, one response, no rendering. That is the whole interaction. So the useful question is not "does my site work" but "how much readable text is in the response, and are my facts among it".

When we scan a page we count the readable characters in that raw HTML and check whether the phone number, address and opening hours appear in it at all. A page that is a shell scores very few characters and hides every fact — that combination is what a client-rendered site looks like from outside.

How to see it yourself

If your address is missing from all three, it is missing for the assistant too.

What to do about it

You do not have to rebuild the site. The goal is that the facts exist somewhere in the served HTML, and there are three ordinary ways to get there:

Straight answers

Do any AI crawlers run JavaScript?

Assume not. The crawlers used by ChatGPT, Claude and Perplexity fetch HTML; building on the assumption that one of them might render is a risk with no upside, because the fix also helps the ones that do not.

Does this apply to React, Vue or Angular sites?

It applies to any site that renders content in the browser rather than on the server. All three can server-render, and that is the setting that matters here — not the framework itself.

My site scores well on speed tests. Isn't that enough?

No. Speed tests run JavaScript. They measure how quickly the rendered page appears to a browser, which is a different question from what arrives in the raw HTML.

Will schema markup fix a JavaScript-rendered site?

It fixes the facts, if the markup is in the served HTML rather than injected after load. It does not make the rest of your page readable.

Related

Where does your site stand? The scan is free, takes about 60 seconds, and needs no account. It fetches your homepage exactly the way GPTBot, ClaudeBot and PerplexityBot do and tells you what they receive.